1. Field of the Invention
The present invention relates to a multicast technique for an IP-TV and, more particularly, to a multicasting technique for an IP-TV employing a transport multiprotocol label switching (T-MPLS) multicasting technique and an optical multicasting technique.
2. Description of the Related Art
In general, in order to provide a broadcast service for an IP-TV, IP traffic is duplicated and transferred to desired subscribers to allow them to share the same data. This has been supported by using a multicasting technique utilizing an IP router in a network.
IP multicasting requires a multicasting protocol such as a protocol independent multicast-sparse mode (PIM-SM), and therefore, an IP router is essential to operate it.
However, when packets pass through several IP routers, the packets may collide, possibly degrading signal quality at a final reception end.
In addition, in order to transfer a large capacity of TV channels to a certain area all at once, a high performance router is required, network controlling is complicated, and a network operation is ineffective.
Thus, a multicasting method capable of multicasting a large capacity of IP-TV data without an IP router, preventing degradation of a signal quality, increasing network efficiency, and simply controlling a network is required.
A transport multiprotocol label switching (T-MPLS) technique, which has been developed by ITU-T, complements the drawbacks of a packet transmission by applying an operation, administration & maintenance (OAM) for high reliability, the merits of an existing synchronous optical NET work/synchronous digital hierarchy (SONET/SDH) technique, and a protection switching technique to an MPLS technique.
However, a multicasting technique using T-MPLS and a multicasting technique in a hybrid form, interworking with an optical switch, are yet to be developed.
For reference, currently, G.8112 defines an interface with respect to the T-MPLS network, Y.1720 recommends a protection switching method with respect to the T-MPLS network, and Y.1711 recommends a T-MPLS OAM.